1. Field of the Invention
The invention relates to an image processing module. Particularly, the invention relates to an image dithering module suitable for image processing.
2. Description of Related Art
Generally, due to characteristics of liquid crystal molecules, when the liquid crystal is driven, a display driving device generally uses a frame inversion technique to drive pixels on a display panel through voltages of positive and negative polarities, so that polarities of the liquid crystal molecules are frequently inverted. However, since the voltages of different polarities may have some offsets, tilt angles of the liquid crystal molecules are different, and a color shift phenomenon is occurred between pixels. Therefore, when a plurality of frames is sequentially displayed, the pixels of each frame are all driven by a voltage of the positive polarity or the negative polarity, and are alternately displayed, and now the image frame may have a flicker phenomenon. In order to mitigate the flicker phenomenon of the image frames, the conventional technique develops a line inversion mode and a dot inversion mode to drive the liquid crystal display (LCD) panel. In this way, the color viewed by human eyes is an average of the pixels of the positive polarity and the negative polarity, and the flicker phenomenon is not occurred when the frames are switched.
On the other hand, considering the cost, a bit number of a driving device of the LCD panel is probably smaller than a grayscale depth required to be performed by the image frame. Now, in order to reconstruct the grayscales, a frame rate control (FRC) technique is generally used to implement modulation of a time axis, or an approach of a spatial domain grayscale average is used for implementation. When the FRC technique is used, a cycle pattern capable of being regularly appeared on the time axis is required to be found, so that values of a part of the pixels are interpolated grayscale values. Moreover, during the interpolation, polarity driving relationship of the pixels is required to be noticed, so as to avoid abnormal phenomenon of the image frame such as rolling lines or the flicker phenomenon, etc. Moreover, when the approach of the spatial domain grayscale average is used to implement the FRC technique, if a fixed interpolation pattern is used, abnormity of the image frames is easy to be perceived by eyes.